In personal communications systems such as cell phones, low cost, high performance and reliability are important and ongoing goals. To reduce costs in such modern communications devices, there is a trend to convert analog circuits into digital architectures that can be more easily implemented in integrated circuit chips and/or in embedded circuit devices and to integrate previously discrete devices. To make and operate a low cost communications device, some components are stressed up to and beyond normal operation parameters for brief periods of time. Over time, an accumulation of stress applied to the components can slowly cause progressive degradation of the components and result in eventual failure to meet a desired component or system specification.
During the design process, guard band margins are included within the design to accommodate parameter drift over the life of the product. The conventional reliability method works for the cases where the performance parameter degradation is linear in a log-degradation versus log-time space. End of life (EOL) parameter drift is conventionally predicted based on a straight line extrapolation using data obtained from short term accelerated testing. The conventional method can overestimate the amount of EOL parameter drift and therefore result in conservative guard band margins. This can result in less competitive products that consume more area and power.